DESCRIPTION: The circadian clock regulates a wide array of behavioral, physiological, and biochemical phenomena in eukaryotes and some prokaryotes. In fact, dysfunction of the circadian clock can lead to severe medical disorders in man. The broad objective of this project is to understand the molecular circuitry underlying circadian behavior. In Drosophila, mutational analyses have identified genes that are important for clock function. The period (per) and timeless (tim) genes encode components of the circadian timekeeping apparatus, or oscillator. An important aspect of oscillator function is related to the ability of per protein (PER) and tim protein (TIM) to regulate the circadian synthesis of their own mRNAs (i.e., the circadian feedback loop), which are synchronously expressed in many neuronal and non-neuronal tissues. The first aim of this project is to identify and characterize cis-sequences that regulate PER/TIM-dependent circadian transcription. Of particular interest will be the complexity, conservation and behavioral importance of these sequences. Specifically Hardin and colleagues plan to (1) define specific sequences required for circadian regulation within a 69 bp per upstream fragment that drives robust mRNA cycling; (2) determine whether this 69 bp clock control fragment is required for behavioral rescue; and (3) determine whether tim clock control sequences are observed. The second aim is to characterize the factors that regulate PER/TIM-dependent circadian transcription. The specific objectives are to: (1) identify factors that mediate circadian transcription by binding to clock control sequences; and (2) characterize clock regulatory factors to define their regulation and possible interactions with PER and/or TIM. The final aim of this proposal examines the relationship between oscillators in different tissues. The specific objecttives are to: (1) determine whether oscillators are autonomous in non-neuronal tissues; (2) determine whether the head is required for entraining oscillators in the body; (3) determine whether feedback loop oscillators in the head influence an oscillator in the body.